240z tune carburetors

datsunnyit

Well-Known Forum User
Hi all.
for tune-up the HITACHI CARB. 240Z is necessary :
chek oil level inside carburetor dome ( level between min and max line )

disconnect front and rear carb.
For disconnect the 2� carb is necessary:

loose the screw A ( FAST IDLE MIN RPM )
loose balance screw B
disconnect CHOKE CABLE (C) for front carburetor and other cable for 2�carburetor.

the small arm/lever D don't touch the balance connection
remove the small arm connection E ( the foot accelerator inside the car not connectet at carburetor )


closed the NUT under the front and rear carb. and after open the nut under front and rear carburetor.
open about 2 turn around (+ or - 1.95 turn)
see table chart ambient temperature 32�C and altitude 20-50m over sea level.


set/tune the mim RPM between 600 -700 RPM for 1� carburetor
use FLOWMETER on front carburetor for 1-2 seconds max ( see the level of ball in the scale of flowmeter)

connect the 2� carb at 1� carb with FAST IDLE MIN RPM (A) and BALANCE SCREW (B) and ARM/LEVER (D) and connect (E)


tune the 2� carburetor with throttle screw.
rotate the screw in one direction on opposite direction.
connect the FLOWMETER on 2� carburetor
the ball inside the scale of flow meter have the same value of 1� carburetor

QUESTION A)
When in FRONT CARBURETOR ( near radiator ) the screw for open/close the throttle valve is complete rotate in one direction, the trottle is 100% closed ?
if 100% closed , the air not go at the engine and the engine dead. is correct ?


QUESTION B)
When in FRONT CARBURETOR ( near radiator ) the screw for open/close the throttle valve is complete rotate in one direction, the trottle is NOT 100% closed ?
if IS NOT 100% closed , the air go at the engine and the engine NOT dead. is correct ?

QUESTION C)

anyone have a simple guide step by step ?
no long line to translate
short and simple phrase

thanks
regards
 

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Jimbo

1978 260z in yellow
Club Member
follow this guide
http://britishclassicmotors.com/3301.html

basically yes to question 1 and 2.

you need to get the engine running before you can properly tune it by setting the carbs to basic settings.
once running then you can adjust the individual throttle stop screws and balance the carburetors. and yes both carburetors will need to have the link removed.

once up to temperature you can adjust the mixture following the guide i sent you.
 

datsunnyit

Well-Known Forum User
If mixture air fuel is rich ( yellow color with gunson colortune), how create the right mixture in white blue color?
Is necessary turn in one direction or opposite direction only the nut under the carburetor previous set with altitude temperature chart?
Or rotate only the screw for throttle valve?
 

Jimbo

1978 260z in yellow
Club Member
basically you need to lift the slide in the carburetta by a very small amount using a lifting pin built into the side of the carburetor.
if the engine speeds up the carb is too rich so screw the nut underneath in by one quarter turn, if the engine dies then its too lean so unscrew the nut under neath by one quarter turn
next repeat the lifting pin bit and see what happens.
eventually you will have little/no reaction from the engine when you lift the pin which is where you want it.
this is the basic way to setup the carbs

if you want to use the gunsons colour tune then screw the nut under the carb in and you should see the colour change from yellow to blue.
i personally wouldn't use the gunsons colour tune as the carbs are better set up like i showed you in the link.
 
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